Roofing squares, from the footprint.
Tape the house from the ground, add the overhang, and let the pitch do the rest. You get the roof surface in squares, squares with your waste, and the bundles to order.
Got the squares? Tell Redline "quote 16.5 squares, architectural, one layer off" and it drafts the itemized quote at your prices.
Try Redline freeHow the math works
Footprint plus overhang
Add the overhang to both ends of the length and both ends of the width, then multiply. 40 x 30 with a 1 ft overhang is 42 x 32, or 1,344 sq ft.
Times the pitch factor
A sloped roof has more surface than the ground it covers. The factor is the length of the slope for every 12 inches of level run: the square root of (12 squared plus the rise squared), divided by 12. For a 6/12 roof that's 1.118, so 1,344 sq ft of footprint is 1,502.6 sq ft of roof.
Into squares, plus waste
A square is 100 sq ft of roof, so 1,502.6 sq ft is 15.03 squares. Your 10% waste makes it 16.53.
Bundles
Squares with waste times bundles per square, rounded up. 16.53 x 3 = 49.6, so 50 bundles.
Same house, four pitches
40 x 30 footprint with a 1 ft overhang (1,344 sq ft), 10% waste, 3 bundles per square.
| Pitch | Pitch factor | Roof surface | Squares | With 10% waste | Bundles |
|---|---|---|---|---|---|
| 4/12 | 1.054 | 1,417 sq ft | 14.17 | 15.58 | 47 |
| 6/12 | 1.118 | 1,503 sq ft | 15.03 | 16.53 | 50 |
| 8/12 | 1.202 | 1,615 sq ft | 16.15 | 17.77 | 54 |
| 12/12 | 1.414 | 1,901 sq ft | 19.01 | 20.91 | 63 |
Plain geometry on one example house. Going from 4/12 to 12/12 adds almost 5 squares of roof surface on the same footprint, which is why the pitch matters on every quote.
What to watch for
- One pitch at a time. The factor holds for gable and hip roofs when every plane has the same pitch. A 3/12 porch roof on an 8/12 house is two runs of the calculator, added together.
- Dormers, bump-outs and the garage each get measured as their own section.
- Not in the squares: starter strip, hip and ridge cap, drip edge, ice and water shield and step flashing. Those go by the linear foot or the roll, so count them separately.
- Bundles per square come off the wrapper. Plenty of lines pack 3 to a square, heavier shingles can pack more. Check the one you're ordering.
- Waste is yours to set. A plain gable wastes less than a cut-up hip roof with valleys. Use what your own past jobs ran.
- Tear-off is quoted on the surface, not the order. Use the squares without waste for the tear-off line.
Questions contractors ask
What is a roofing square?
100 square feet of roof surface, measured on the slope. Shingles, underlayment and tear-off are usually priced per square, so it's the number the rest of the quote hangs on.
Why start from the footprint instead of the roof?
Because you can measure it safely from the ground in a few minutes. The pitch factor turns the flat footprint into sloped surface. If you've measured each plane on the roof, or you have a measurement report, add those areas up and divide by 100 instead.
How do I find the pitch?
Hold a level flat against the roof or a rafter, mark 12 inches along it, and measure straight up to the roof. That height is the rise. The roof pitch calculator handles other measurements and gives you the angle too.
How does Redline use the squares?
They go straight into the quote. Message "quote the Hendersons: 17 squares architectural, one layer off, 30% deposit", or send photos from the roof, and Redline drafts the itemized quote at your prices. Good, better and best options live in the quote composer, opened from Money (Solo and up). It's saved on the customer's file on any plan; you present it in person or email it from your own Gmail. When the roof's done, invoice the balance with a card pay link on Solo, $29 a month.
More for roofers
Keep reading
- Roof pitch calculatorRise and run into pitch, degrees, slope and the pitch factor.
- Gutter calculatorEave length and your rules into gutter feet, downspouts, elbows and hangers.
- Quotes and estimatesItemized quotes by chat or from a photo, with a deposit. Options and tax in the composer.
- Job profit calculatorSee what a job really makes after materials, labor and overhead.